{"id":"CVE-2025-66646","aliases":["EUVD-2025-203929","GHSA-v8gx-q9m6-5xm9"],"status":"published","title":"RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass","description":"RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.","severity":{"version":"4.0","score":1.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-08","score":0.00679,"percentile":0.52595,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-476"],"published":"2025-12-17T19:18:08Z","modified":"2026-11-07T02:48:21Z","products":[{"vendor":"riot-os","product":"riot"}],"references":[{"url":"https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-v8gx-q9m6-5xm9","tags":["x_refsource_CONFIRM","Exploit","Patch","Vendor Advisory","advisory"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L411","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L420","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L490","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L532","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L534","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L544","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/pktbuf_static/gnrc_pktbuf_static.c#L150C1-L150C76","tags":["x_refsource_MISC","Product","web"]},{"url":"https://github.com/RIOT-OS/RIOT/releases/tag/2025.10","tags":["x_refsource_MISC","Release Notes","web"]},{"url":"https://github.com/user-attachments/files/23903992/reproducer_1.zip","tags":["x_refsource_MISC","Exploit","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66646.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66646","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2025-66646","title":"RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass","description":"RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.","status":"published","published":"2025-12-17T19:18:08.696Z","modified":"2025-12-17T20:30:49.97Z","cvss":[{"version":"4.0","score":1.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U","level":"low","assessor":"cna"}],"cwes":["CWE-476"],"updated_at":"2026-11-02T14:32:53.157279Z"}],"euvd":[{"id":"EUVD-2025-203929","description":"RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.","status":"published","published":"2025-12-17T19:18:08Z","modified":"2025-12-17T20:30:49Z","cvss":[{"version":"4.0","score":1.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U","level":"low"}],"updated_at":"2026-11-02T19:49:03.481924Z"}],"nvd":[{"id":"CVE-2025-66646","description":"RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.","status":"published","published":"2025-12-17T20:15:56.17Z","modified":"2026-10-13T11:10:00.203Z","cvss":[{"version":"4.0","score":1.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"low","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-476"],"updated_at":"2026-11-02T14:11:51.309584Z"}],"osv":[{"id":"CVE-2025-66646","title":"RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass","description":"RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.","status":"published","published":"2025-12-17T19:18:08.696Z","modified":"2026-11-07T02:48:21.197912889Z","cvss":[{"version":"4.0","score":1.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U","level":"low"}],"cwes":["CWE-476"],"updated_at":"2026-11-07T03:07:58.603715Z"}]}}